Can not use pool created from custom image

[ikopytko]

Describe the bug Templates dialogue is not working if there is a pool created from custom image int the list. Looks like api is not returning offerName for this machine, however it was set when image was created (field is required anyway), and later template cannot choose correct icon for it. Checking for null argument [here] and some default fall back (https://github.com/Azure/BatchExplorer/blob/master/src/app/utils/pool-utils.ts#L86) will help. I was able to recreate this issue with multiple different images.

To Reproduce Steps to reproduce the behavior:

1. Create pool based on custom vm image (ubuntu 16.04)
2. Go to Gallery
3. Use custom or predefined template for job
4. See error

Expected behavior Some default image in case if there is no machine type in data:

Screenshots Messed dialogue: Missed offer in imageReference (pools request):

Logs(console) core.js:6014 ERROR TypeError: Cannot read property 'toLowerCase' of null at Function.iconForOffer (pool-utils.ts:90) at Function.iconForPool (pool-utils.ts:109) at PoolPickerComponent.iconForPool (pool-picker.component.ts:161) at Object.updateDirectives (pool-picker.html:21) at Object.updateDirectives (core.js:44779) at checkAndUpdateView (core.js:44270) at callViewAction (core.js:44636) at execEmbeddedViewsAction (core.js:44593) at checkAndUpdateView (core.js:44271) at callViewAction (core.js:44636)

Version:

• OS: Windows
• Version 2.7.0-stable.418